1. Field of the Invention
The present invention relates to a cramping terminal.
2. Description of the Related Art
A prior art cramping terminal has a substantially U-shaped groove portion which typically is formed by bending a metal plate. A cramping blade is disposed in the groove portion and is formed with a slit. The blade is configured to cut an insulation coating of a wire pushed into the slit, thereby bringing a core of the wire into contact with the inner surface of the slit to establish an electrical connection.
There are two types of prior art cramping blades. In particular, a prior art U-slot cramping blade 5 is shown in FIG. 7, and is made by forming a slit 4 in an upright piece 3 that had been formed by cutting and bending a portion of a bottom wall 2 of a U-shaped groove portion 1. The prior art also includes a side cramping blade 8 as shown in FIG. 8. The side cramping blade 8 is formed by cutting and bending portions of opposite side walls 6 of a groove portion 1 in such a manner as to face each other. With the prior art side cramping blade 8, a pair of holes 7A are formed in the opposite side walls 6 in the same position along the longitudinal direction of the groove portion 1, thereby causing a reduction in the strength.
There also is a demand for adding a side cramping blade to a known cramping terminal 9 with a pair of U-slot cramping blades 5, as shown in FIG. 9, in an effort to improve the reliability of an electrical connection with a wire. In such a case, a side cramping blade 8 has been formed in the cramping terminal 9 as shown in FIG. 10. However, with this prior art design, a hole 9B left in the bottom wall 2 by forming the U-slot cramping blade 8 and the holes 7A of the opposite side walls 6 are in the same position with respect to the longitudinal direction of the groove portion 1. This design, therefore, leaves only a small area of walls, as indicated by the hatched portions in FIG. 11, and hence weakens the connector.
In view of the above problems, an object of the present invention is to provide a cramping terminal which has a groove portion of a higher strength and ensures a more reliable electrical connection.